Method and apparatus for cutting plate-shaped brittle material

Abstract

To assure that a plate-shaped brittle material is exactly cut into two plate pieces, a jig having a thread-shaped projection secured thereto in conformity with a predetermined pattern positionally coincident with a cut groove formed in the plate-shaped brittle material, an elastic member located on the cut groove side of the plate-shaped brittle material, and a plate-shaped brittle material to be cut into two plate pieces are placed on a table of a press machine one above another, and subsequently, a predetermined intensity of pressing power is applied to the jig from above by operating a pressing machine. Alternatively, a jig having a thread-shaped projection secured thereto, an elastic member located on the opposite side relative to the cut groove side of the plate-shaped brittle material, and a plate-shaped brittle material to be cut into two plate pieces may be placed on the press table one above another. Otherwise, a pair of jigs each having a thread-shaped projection secured thereto, a pair of elastic members one of which is located on the cut groove side of a plate-shaped brittle material and other one of which is located on the opposite side relative to the cut groove side of the plate-shaped brittle material, and a plate-shaped brittle material to be cut into two plate pieces may be placed on the press table one above another.

What is claimed is: 
     
       1. A method of cutting a plate-shaped brittle material into two plate pieces, comprising the steps of: forming a cut groove on a first surface of said plate-shaped brittle material in conformity with a predetermined pattern;   placing said plate-shaped brittle material on a flat surface of a press table, the first surface of said plate-shaped brittle material facing the surface of said press table, the surface of said press table remaining flat such that said plate-shaped brittle material does not bend;   superimposing a jig having a thread-shaped projection secured thereto on a second surface of said plate-shaped brittle material opposite to the first surface of said plate-shaped brittle material with an elastic member interposed between said plate-shaped brittle material and said jig, a ridge line of said thread-shaped projection extending in conformity with said predetermined pattern of said cut groove with a constant height as measured in a direction perpendicular to the first surface and the second surface of said plate-shaped brittle material; and   applying a predetermined intensity of compressing force across said elastic member at a right angle relative to the first surface of said plate-shaped brittle material via said jig and said plate-shaped brittle material,   whereby said compressing force generates first tensile stresses in said elastic member, said first tensile stresses generate second tensile stresses in said plate-shaped brittle material by friction between said elastic member and said plate-shaped brittle material, and said second tensile stresses fracture said plate-shaped brittle material in conformity with said predetermined pattern.   
     
     
       2. The method according to claim 1, wherein said thread-shaped projection secured to said jig is formed by allowing said thread-shaped projection to continuously extend in conformity with said predetermined pattern positionally coincident with said cut groove. 
     
     
       3. The method according to claim 1, wherein said thread-shaped projection secured to said jig is formed by allowing said thread-shaped projection to intermittently extend in conformity with said predetermined pattern positionally coincident with said cut groove. 
     
     
       4. The method according to claim 1, wherein an elastic modulus of said elastic member is set to be smaller than that of said plate-shaped brittle material to be cut into two plate pieces.